There are various types of relatively simple rockers or seesaw devices which are typically set up in the practices of physiotherapists, sometimes also in fitness centers, and on which persons place themselves in order to perform exercises. For examples of such devices, reference may be made to AT 411 015 B and to DE 100 04 785 B4.
According to AT 411 015 B, the person exercising stands on a platform that rests on the ground via two rockers that are curved in a vertical plane, such that the platform can seesaw via these rockers. The position of the rockers can be adjusted so as to make the rocking movement of the platform gentler or more abrupt. The person standing on the platform is stimulated to balance himself in such a way that the platform remains horizontal.
An advantage of this device is that it is simple, inexpensive and takes up little space. A disadvantage is that it permits only one degree of freedom of movement, namely a rocking movement in a vertical plane. A further disadvantage is that the characteristic curve of the rocking movement cannot be adjusted during operation of the device.
DE 100 04 785 B4 discloses a stand surface that can be swiveled within a limited angle range about two horizontal axles which are located at a distance above it and are perpendicular to each other. Movement of the platform can be subjected to a mechanical attenuation. The height of the axles above the stand surface and the movement attenuation are adjustable. The angular excursion can be visualized for the user.
This device too is relatively simple and also still inexpensive. Compared to the aforementioned device, it offers a further degree of freedom of movement and adjustable attenuation. A disadvantage is that it takes up quite a lot of space and that it places only minimal demands on the sense of balance.
There are additionally devices which, in cooperation with computers and active drive elements, can move surfaces on which a person is located in up to all six degrees of freedom and which additionally show corresponding images on screens, for example of journeys in virtual space, or informative displays on movement states. Movement and images can optionally be influenced interactively by the person using the installation, or they simply run in the manner of a film and thus exert their action on the person. Such devices are, for example, vehicle simulators used for training purposes. In a somewhat more economical form, they are also used as still very expensive games devices with which, for example in gaming halls or at funfairs, a so-called “virtual reality” can be experienced for a few minutes against payment of a fee.
For examples of such devices, reference may be made to U.S. Pat. No. 5,629,594, DE 199 12 281 A1 and DE 198 46 337 C2.
U.S. Pat. No. 5,629,594 discloses a device which, in connection with a computer, can displace a surface, on which a person is located, in an accelerated movement within a limited range, and can thus ensure that movements which take place in the reality simulated in the computer can be made appreciable in the actual reality of the computer user. The movement is effected by means of electric motors, toothed wheels and toothed racks. This is extremely expensive. In addition, the dynamically controlled electric motors require frequency converters, which cause considerable problems in normal power supply networks.
DE 199 12 281 A1 discloses a riding simulator which can move a dummy horse in three linear directions and in three rotation directions. The movement is effected by means of pneumatic cylinders. Because of the static friction between cylinder and piston, coupled with the elasticity of volume of gases, it is practically impossible to simulate fine movements with alternating directions without causing jolts. On the whole, it is only by using very expensive mechanical components and an extremely intelligent and highly dynamic control system that the arrangement can be produced in approximately the quality specified in the document. The installation is therefore very expensive.
If the construction according to DE 199 12 281 A1 were to be realized with hydraulic drive elements instead of pneumatic elements, the problem of the elasticity of volume of the pressure medium could be avoided. However, a hydraulic installation is also associated with high costs, considerable weight, in some cases unpleasant smells, and, in the event of leaks, the risk of contamination.
According to both U.S. Pat. No. 5,629,594 and DE 199 12 281 A1, constructions are proposed in which, on a base slide movable in one direction, a further slide is mounted which is movable thereon in another direction, etc. until on the last slide the mobile surface is secured. This construction has the effect that the kinematic relationships are at all times easy to understand, but it is very heavy and expensive.
By contrast, DE 198 46 337 C2 discloses a construction according to which the mobile surface is held at three points rotatably on one end of length-adaptable adjusting elements. With the other end, the adjusting elements are also secured rotatably on a stationary base surface. All movements of the mobile surface are effected by suitably coordinated changing of the length of the adjusting elements. Compared to a construction with stacked slides, this construction is much less expensive, even if it requires slightly more computer performance. However, this results in a very bulky structure which, in the assembled state, can be transported only with great difficulty.
The length-adaptable adjusting elements according to DE 198 46 337 C2 are not described in detail in the document. From the drawing and arrangement, however, it is evident that they are pneumatic or hydraulic cylinder/piston arrangements. With these, the problems already mentioned above also arise.